a. Field of Invention
The invention relates to an electronic overcurrent tripping device for multi-phase circuit breakers with a short circuit current detector, a comparison circuit as well as a tripping command transmitter.
b. Description of the Prior Art
In reverse-power relays it is known (U.S. Pat. No. 4,100,587) to sum up the instantaneous power values. The sum of the instantaneous powers is fed to a low-pass filter in which the a-c components are filtered out so that the active powers of the three phases are added. The result is fed to a comparator, in which the sum is compared with a fixed, set reference value.
An electronic overcurrent tripping device for the detection of overcurrents and short circuits and the tripping of a circuit breaker is described in Siemens Energie-Technik 2 (1980), No. 12, pages 499 to 502.